This invention relates to a wiper motor control.
Many modern vehicles include a single rear window wiper and a rear window defroster. The wiper arm is moved in a reciprocating motion across the rear window by a wiper motor. However, many environmental factors can effect the movement of the wiper arm and blade. For example, during winter weather, the wiper blade may "freeze" to the rear window. Cold temperatures may lower the battery voltage of the vehicle causing the wiper arm to move at a much slower speed. Hot temperatures can have the opposite effect. Ice covering the rear window may cause the wiper blade to "slide" across the rear window. A large amount of snow may prevent the wiper blade from moving through its entire range of movement. It would be desirable to provide a wiper motor control circuit for managing these conditions.
Most modern vehicles further include a rear window defroster. Typically, the rear window defroster consists of a power switch and a resistive electrical filament strip bonded to the inside of the rear window. One end of the resistive filament is connected to a power source and the opposite end of the resistive filament is connected to ground. When the defroster is switched on, current from the power source flows through the resistive filament to ground thereby warming the filament. The warm filament heats the rear window.
In most modern vehicles, the rear window defroster system and the rear window wiper system are packaged close to each other yet assembled and operated separately. It would be desirable to capitalize upon the packaging proximity and integrate the rear window defroster system and the rear window wiper system to reduce parts, conserve packaging space, decrease cost, and increase reliability. Further, it would be desirable to use the defroster filament strip as both a load sense resistor and a temperature sensor in the wiper motor control circuit.